1. Field of the Invention
This invention relates to an image processing method and apparatus thereof, and especially to a method and an apparatus for generating an image with shallow depth of field.
2. Description of Related Art
With the development of optical technology, cameras with adjustable diaphragms, shutters, and even replaceable lenses are gradually more and more popular. Cameras are also becoming multi-functioned. When using a camera, in order to highlight a theme of a captured image, a so-called shallow depth of field technique is used, wherein the camera lens is focused on a specific scope of a distance in the image, so the image of an object within the scope of the distance is clearly formed, and simultaneously, the images of the objects outside the scope of the distance are blurred.
However, the shallow depth of field effect in common camera lenses are limited. In order to obtain a better shallow depth of field effect, then lenses with large apertures must be used in order to enhance the blurring of long distance objects, and highlight the clearly formed theme from the background. Furthermore, lenses with large apertures have a bulky body and pricey cost, and is not equipped by common consumption cameras.
Another method of creating a shallow depth of field effect is through the image post-processing. The image processing method is used to estimate the depth relationship, and then accordingly enhance a blur level of long distance objects, so as to highlight the theme. However, this method can only rely on general perception to determine the blur level of an object. Regarding objects outside a focal range, the blur level is then hard to estimate, and may cause inaccuracies. As a result, after processing the image, the image may be discontinuous or unnatural.
Thus, how to obtain the correct depth information of an object in an image, so as to assist in differentiating the blur level of each object, and produce a better shallow depth of field effect, is a main challenge those in the field want to overcome.